This invention relates generally to network testing, and in particular to automatically configuring the transmit and receive paths of a network tester to interface with a network.
Packet-switched networks such as Frame Relay have become popular for internet access, LAN (Local Area Network)-to-LAN connection, automated teller machine connection, point-of-sale cash registers, small business and retail store access to central data services, and other wide area data communication services. To meet the increasing demands for installation and basic throughput testing of packet-switched networks, test equipment is being developed that can both diagnose problems and passively monitor Frame Relay traffic in both directions to determine or verify network performance.
In connecting such test equipment to a network port, one important aspect of testing before throughput can even be monitored is to determine which pair of a four-wire cable or transmission link is the transmit pair and which is the receive pair. Wire mapping techniques are available, but are slow and tedious. They are carried out with the cabling disconnected, and require extra equipment such as remote terminations. It would be desirable to determine which pair is which while traffic is being throughput on the network.
In accordance with the present invention, a method and apparatus are provided for automatically configuring the transmit and receive paths of a network tester by determining which path is carrying transmit signals and which path is carrying receive signals while the tester is connected to a network under test. Initially, both the transmit and receive paths in a transmission link or cable are monitored simultaneously. That is, both pairs of wire in a four-wire cable initially are coupled to a receiver in the tester.
When a receive signal indication is given by the tester, it is an indication of traffic on one of the two transmission paths. The tester automatically then configures its interface to designate a first one of the two paths as the receive path and tests the configuration to see if a signal on the first path is indeed received. If a signal is received, the designated receive path is in fact the receive path, and by deduction, the other path is the transmit path. If no signal is received, however, then the tester automatically reconfigures its interface to designate the second path as the receive path and tests the new configuration to determine if a signal is received. If the signal is lost, meaning that the network traffic is sporadic or has stopped altogether, the tester will automatically repeat the configuration testing. Once the receive path is identified, then the transmit path is set opposite to the receive path.
This method of automatically configuring the transmit and receive paths of the tester interface relieves the user of the tester from knowing, or having to determine, which path is which before using the tester. While the embodiment shown and described herein is with reference to a multiple-wire network cable having at least two twisted pairs of wire, for example, a four-wire cable system, it should be noted that this technique works equally well for T1, E1, or DDS transmission interfaces, and can be applied to other full duplex metallic interfaces such as T3 or E3.
It is therefore one object of the present invention to automatically determine which path of a network transmission link having separate transmit and receive paths is the transmit path and which is the receive path.
It is another object of the present invention to automatically configure the transmit and receive paths of a tester interface.
It is a further object of the present invention to provide a method for determining transmit and receive paths in a network transmission link for a wide range of service levels and protocols.
Other objects, features, and advantages of the present invention will become obvious to those having ordinary skill in the art upon a reading of the following description when taken in conjunction with the accompanying drawings.